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. 2019 Jun 27;13:291. doi: 10.3389/fncel.2019.00291

FIGURE 2.

FIGURE 2

hM4DGi activation leads to a reduction in evoked neurotransmitter release and a decrease in action potential firing frequency. (A–C) Neurons transfected with cDNAs encoding hM4DGi, mCherry, and oCHIEF were identified and whole-cell currents were measured in voltage-clamp recordings of adjacent untransfected neurons (scale bar in A,D: 10 μm). In neurons in which brief illumination with blue light (denoted by blue bar in B) resulted in short-latency EPSCs, DREADD agonist was applied. Black and blue traces depict EPSCs before and after drug application. Scale bars: 10 ms, 500 pA. (C) In n = 12 experiments, agonist application led to a significant reduction in EPSC amplitude (median amplitudes 200.3 and 39.1 pA before and after drug application, respectively, Wilcoxon Signed Rank Test Z = 3.04, p = 0.0024). (D–F) Neurons were transfected with hM4DGi and mCherry, and whole-cell current clamp recordings were made from transfected neurons to measure the action potential frequency before and after application of DREADD agonist (black and blue traces in E). Scale bars: 1 s and 5 mV. (F) In n = 12 experiments, agonist application led to a significant reduction of AP frequency (median action potential frequencies 1.03 and 0.74 Hz before and after drug application; Wilcoxon Signed Rank Test Z = 2.29, p = 0.022). ∗p < 0.05, ∗∗p < 0.01.